Abstract: Background and Objective: Citrullus spp. seeds are used as soup thickeners in most West African countries. They provide protein thereby solving protein malnutrition problem. Citrullus lanatus seed as a member of the family is usually discarded after the mesocarp has been consumed. The aim of the study was to investigate the potentials of watermelon seed (Citrullus lanatus) as a soup thickener. Materials and Methods: The watermelon seed was sundried, dehulled and ground into flour. The flour was subjected to chemical analyses using standard methods (AOAC). The anti-nutritional factors were analyzed using Pearson method. Functional properties were carried out according to the method of Onwuka. The watermelon seeds flour were prepared and evaluated using a 9-point Hedonic scale and data generated were subjected to one way analysis of variance. Results: The study revealed that watermelon seed contains high amounts of crude protein (24.33%), fat (28.27%) and fibre (4.33%). The seed is high in calcium (8.22 mg/100 g), Vitamin A (321.96 mg/100 g) and D (256.56 mg/100 g) respectively. The seed is low in anti-nutrients but has high water and oil absorption capacities (106.44 and 133.11%). There was no significant difference (p>0.05) between the soups prepared using watermelon and melon seeds. Conclusion: The study revealed that watermelon seed is high in nutrients and compared favourably with melon soup. Thus watermelon seed can serve as a soup thickener.